Technical Field
The present disclosure relates to a high pressure tank, a manufacturing method of a high pressure tank, and an inspection method of a sealing characteristic of a test piece.
Description of Related Art
10003) A mouth piece (a boss) for a high pressure tank, described in Published Japanese Translation of PCT application No. 2012-514727 (JP-A-2012-514727), may include a keyway on an inner side thereof, and may further includes a ring lip extending outwardly in a radial direction from the keyway. An inner surface of the ring lip may have an inclined surface. The inclined surface may be inclined toward an end side as it goes from an inner end to an outer end in the radial direction.
The high pressure tank can be formed without considering the following facts: gas stored in the high pressure tank accumulates on an interface between a liner and the mouth piece through a microgap therebetween; and when the gas passes through the liner itself and accumulates on the interface, or particularly when a sealing characteristic between the liner and the mouth piece decreases at a low pressure, the gas may accumulate on the interface between the mouth piece and the liner.
FIGS. 17 and 18 are views to describe the gas accumulating on the interface between the liner and the mouth piece. Note that a configuration illustrated in FIGS. 17 and 18 is not well known. FIG. 18 is an enlarged view of a region 16 illustrated in FIG. 17.
A high pressure tank 1000 includes a liner 1020 and a mouth piece 1100, and stores high-pressure gas therein. The gas thus stored may enter an interface between the liner 1020 and the mouth piece 1100 from a boundary K between the liner 1020 and the mouth piece 1100. In a case of FIG. 18, when the gas is discharged suddenly and a tank internal pressure is rapidly decreased from a high pressure to a low pressure, a pressure of the gas accumulating in the interface may become larger than the tank internal pressure due to a time lag before the gas that enters the interface returns to the tank internal space, so that a force toward the internal space is applied to the liner 1020 so as to separate the liner 1020 from the mouth piece 1100, as illustrated in FIG. 18.
Particularly, when a pressure of the gas stored in the high pressure tank 1000 is small, a contact pressure on the interface due to an internal pressure may also become small. That is, a force that causes the liner 1020 to be pressed against the mouth piece 1100 due to the gas pressure may become weak. In this case, it can be difficult to secure a sealing characteristic, thereby causing such a problem that the gas easily enters the interface.